That's a feature (Surge Pricing). The official reason is to get more cars on the road, but I bet they're not unhappy about pocketing more consumer money either.
Surge Pricing is illegal in Berlin, and probably other European countries. And I imagine the illegality of price gouging ("surge pricing") while also skirting taxi regulation will be expanded dramatically in the coming years, all across much of Europe and blue states.
Yes, you can profit when you find loopholes in regulations that your competitors can't take advantage of. Color me shocked.